The purpose of this Phase II project is to further develop and evaluate the efficacy of a computerized self-help cessation intervention for adolescent and young adult smokeless tobacco (ST) users. The program utilizes a small handheld computer to deliver a scheduled gradual reduction of the frequency and duration of dips or chews until cessation is achieved. In Phase I, the feasibility of the program was tested with 30 smokeless tobacco users age 16 to 23 who utilized the program over a six week period. At the end of treatment, 20% of the intent to treat sample and 33% of the treatment completers were continuously abstinent and met 7-day point prevalence abstinence confirmed by saliva cotinine analysis. Those who failed to quit reduced their ST use by 53%. Subjects rated the program positively, but noted that delivery of the program on the prototyping research units used for the study were difficult to carry and hard to use regularly. For Phase II, the program algorithms will be further refined based on Phase I feedback and the program will be ported to a newly developed special purpose device (QuitKey) which is about the size of a keychain FOB and easy to carry. In addition, a snuff can lid holder will be engineered to allow the user to carry the device with their snuff can, thereby further improving ease of use and compliance. The Phase II program will then be evaluated in a multi-site trial of 350 adolescent and young adult ST users. Subjects will be randomly assigned to receive either a manual self-help program (Enough Snuff) or the QuitKey for Dippers and Chewers (QuitKey DC). ST use and related variables will be assessed at baseline and at 8 and 26 weeks post treatment initiation. The results of the study will provide data on the relative efficacy of these two minimal contacts, self-help treatments for adolescent and young adult ST users, and will determine if the proposed product is a viable cessation option for young ST users for whom few effective cessation options are available. By intervening early in the drug use trajectory of ST users, cessation can be achieved before long-term physical dependence and negative health effects develop. [unreadable] [unreadable] [unreadable]